Well, got hosed again!
Phone is now stuck at the white htc Incredible start screen. What I did to arrive at this lovely place was:
1) booted to HBOOT to check if I was still S-off (I was);
2) flashed HBOOT 1.07 from a PB31IMG.ZIP file, booted into it (and it showed that I was still unlocked);
3) flashed CWM;
4) put the updated 4.08.605.2 ROM file (that you linked above) as well as a new radio file (from that same thread) on the SD card;
5) booted into CWM and had it flash the ROM update, which appeared to complete successfully;
6) had CWM try to flash the radio, but it aborted;
7) rebooted to HBOOT, just to see if the radio updated (it didn't);
8) rebooted normally to see if the system would start up, and got stuck at that white screen;
9) pulled battery to completely cycle everything, but still no joy.
What I did not do was flash superuser again, but didn't think that I had to. Did I? Or did I mess up somewhere else along the line?